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Author |
Schnack-Schiel, S.B.; Dieckmann, G.S.; Kattner, G.; Thomas, D.N. |
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Title |
Copepods in summer platelet ice in the eastern Weddell Sea, Antarctica |
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Journal Article |
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Year |
2004 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
27 |
Issue |
8 |
Pages |
502-506 |
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Abstract  |
Copepods in platelet-ice layers underlying fast ice and in the water column below were studied at Drescher Inlet, eastern Weddell Sea in February 1998. Three copepod species were found: Drescheriella glacialis and Paralabidocera antarctica occurred in platelet-ice layers, while Stephos longipes was only present in the water column. The distribution of all species varied considerably between station and depth. D. glacialis dominated the platelet-ice community and occurred at all five platelet-ice sampling sites, except one, with numbers of up to 26 ind. l?¹. In contrast, P. antarctica was only found in low numbers (up to 2 ind. l?¹) at one site. The total copepod abundance in the platelet ice was not associated with algal biomass, although it was strongly correlated with high ammonium concentrations (up to 9 µM) in the interstitial water between the platelets. This is the first indirect evidence to support the hypothesis that zooplankton excretion can partly account for the high ammonium values often found in platelet-ice layers. |
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Springer-Verlag |
Place of Publication |
Heidelberg |
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0722-4060 |
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Notes |
Short note |
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no |
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Call Number |
refbase @ admin @ Schnack-Schiel++2004 |
Serial |
752 |
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Author |
Arrigo, K.R.; Thomas, D.N. |
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Title |
Large scale importance of sea ice biology in the Southern Ocean |
Type |
Journal Article |
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Year |
2004 |
Publication |
Antarctic Science |
Abbreviated Journal |
Antarct Sci |
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Volume |
16 |
Issue |
4 |
Pages |
471-486 |
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Keywords |
algae; Antarctic; biogeochemistry; carbon cycle; primary production; Full Data Records |
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Abstract |
Despite being one of the largest biomes on earth, sea ice ecosystems have only received intensive study over the past 30 years. Sea ice is a unique habitat for assemblages of bacteria, algae, protists, and invertebrates that grow within a matrix dominated by strong gradients in temperature, salinity, nutrients, and UV and visible radiation. A suite of physiological adaptations allow these organisms to thrive in ice, where their enormous biomass makes them a fundamental component of polar ecosystems. Sea ice algae are an important energy and nutritional source for invertebrates such as juvenile krill, accounting for up to 25% of total annual primary production in ice-covered waters. The ability of ice algae to produce large amounts of UV absorbing compounds such as mycosporine-like amino acids makes them even more important to organisms like krill that can incorporate these sunscreens into their own tissues. Furthermore, the nutrient and light conditions in which sea ice algae thrive induce them to synthesize enhanced concentrations of polyunsaturated fatty acids, a vital constituent of the diet of grazing organisms, especially during winter. Finally, sea ice bacteria and algae have become the focus of biotechnology, and are being considered as proxies of possible life forms on ice-covered extraterrestrial systems. An analysis of how the balance between sea ice and pelagic production might change under a warming scenario indicates that when current levels of primary production and changes in the areas of sea ice habitats are taken into account, the expected 25% loss of sea ice over the next century would increase primary production in the Southern Ocean by approximately 10%, resulting in a slight negative feedback on climate warming. |
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Cambridge University Press |
Place of Publication |
Cambridge |
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0954-1020 |
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Review |
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Call Number |
refbase @ admin @ Arrigo+Thomas2004 |
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729 |
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Author |
Thomas, D.N.; Gleitz, M. |
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Title |
Allocation of photoassimilated carbon into major algal metabolite fractions: Variation between two diatom species isolated from the Weddell Sea (Antarctica) |
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Journal Article |
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Year |
1993 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
13 |
Issue |
4 |
Pages |
281-286 |
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Keywords |
carbon fixation; metabolites; biomass; Nitzschia curta; Chaetoceros; Psw; Weddell Sea |
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Abstract |
Distribution of photoassimilated carbon into major metabolite classes differed between two Antarctic diatom species, Nitzschia curta and a small unicellular Chaetoceros sp.. Time course uptake studies (over 54 h) revealed that¹?C allocation appeared to be equilibrated after approximately 8 h at light saturated photosynthesis. During short term dark periods (6 h), polysaccharides as well as low-molecular-weight compounds were catabolised to sustain protein synthesis in the dark, whilst lipid reserves were not mobilised for this process. Experiments with these two species were conducted at 0 and -1.5 degree C, although no difference in the distribution of radiolabel was measured between the two temperatures. It is hypothesised that under near-optimal conditions fast growing species are characterised by a high carbon turnover associated with a rapid flow of newly assimilated carbon into polymeric compound classes. On the other hand, slower growing species (such as N. curta) may store a significant amount of surplus carbon in the low-molecular-weight metabolite fraction. Species specific preferences were observed when comparing the accumulation of radiolabel into the lipid pools. |
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Springer-Verlag |
Place of Publication |
Heidelberg |
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ISSN |
0722-4060 |
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Notes |
Bibliogr.: 48 ref.; Marine |
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no |
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Call Number |
refbase @ admin @ Thomas+Gleitz1993 |
Serial |
760 |
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Author |
Gleitz, M.; Rutgers v d Loeff, M.; Thomas, D.N.; Dieckmann, G.S.; Millero, F.J. |
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Title |
Comparison of summer and winter inorganic carbon, oxygen and nutrient concentrations in Antarctic sea ice brine |
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Journal Article |
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Year |
1995 |
Publication |
Marine Chemistry |
Abbreviated Journal |
Mar Chem |
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51 |
Issue |
2 |
Pages |
81-91 |
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Keywords |
dissolved oxygen; inorganic compounds; summer; winter; nutrients (mineral); Antarctic zone; sea ice; brines; carbon; chemical composition; Psw; Weddell Sea; polar zones; polar regions; nutrients |
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Abstract |
During summer (January 1991) and winter (April 1992) cruises to the southern Weddell Sea (Antarctica), brine samples were collected from first year sea ice and analysed for salinity, temperature, dissolved oxygen and major nutrient concentrations. Additionally, the carbonate system was determined from measurements of pH and total alkalinity. During winter, brine chemical composition was largely determined by seawater concentration in the course of freezing. Brine temperatures ranged from -1.9 to -6.7 °C. Precipitation of calcium carbonate was not observed at the corresponding salinity range of 34 to 108. Removal of carbon from the total inorganic carbon pool (up to 500 µmol Ct kg?¹) was related to reduced nutrient concentrations, indicating the presence of photosynthetically active ice algal assemblages in the winter sea ice. However, nutrient and inorganic carbon concentrations did generally not reach growth limiting levels for phytoplankton. The combined effect of photosynthesis and physical concentration resulted in O? concentrations of up to 650 µmol kg?¹. During summer, brine salinities ranged from 21 to 41 with most values >28, showing that the net effect of freezing and melting on brine chemical composition was generally slight. Opposite to the winter situation, brine chemical composition was strongly influenced by biological activity. Photosynthetic carbon assimilation resulted in a Ct depletion of up to 1200 µmol kg?¹, which was associated with CO? (aq) exhaustion and O? concentrations as high as 933 µmol kg?¹. The concurrent depletion of major nutrients generally corresponded to uptake ratios predicted from phytoplankton biochemical composition. Primary productivity in summer sea ice is apparently sustained until inorganic resources are fully exhausted, resulting in brine chemical compositions that differ profoundly from those of surface waters. This may have important implications for pathways of ice algal carbon acquisition, carbon isotope fractionation as well as for species distribution in the open water phytoplankton. |
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Publisher |
Elsevier Science B.V. |
Place of Publication |
Amsterdam |
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0304-4203 |
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no |
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Call Number |
refbase @ admin @ Gleitz++1995 |
Serial |
733 |
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Author |
Lakaniemi, A.-M.; Hulatt, C.J.; Wakeman, K.D.; Thomas, D.N.; Puhakka, J.A. |
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Title |
Eukaryotic and prokaryotic microbial communities during microalgal biomass production |
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Journal Article |
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Year |
2012 |
Publication |
Bioresource Technology |
Abbreviated Journal |
Bioresour Technol |
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124 |
Issue |
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Pages |
387-393 |
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Keywords |
Bacteria/classification/genetics/metabolism; *Biomass; Electrophoresis, Polyacrylamide Gel; Eukaryotic Cells; Microalgae/*metabolism; Phylogeny; Polymerase Chain Reaction; Prokaryotic Cells |
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Abstract |
Eukaryotic and bacterial communities were characterized and quantified in microalgal photobioreactor cultures of freshwater Chlorella vulgaris and marine Dunaliella tertiolecta. The microalgae exhibited good growth, whilst both cultures contained diverse bacterial communities. Both cultures included Proteobacteria and Bacteroidetes, while C. vulgaris cultures also contained Actinobacteria. The bacterial genera present in the cultures were different due to different growth medium salinities and possibly different extracellular products. Bacterial community profiles were relatively stable in D. tertiolecta cultures but not in C. vulgaris cultures likely due to presence of ciliates (Colpoda sp.) in the latter. The presence of ciliates did not, however, cause decrease in total number of C. vulgaris or bacteria during 14 days of cultivation. Quantitative PCR (qPCR) reliably showed relative microalgal and bacterial cell numbers in the batch cultures with stable microbial communities, but was not effective when bacterial communities varied. Raw culture samples were successfully used as qPCR templates. |
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Address |
Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland. aino-maija.lakaniemi@tut.fi |
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Language |
English |
Summary Language |
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ISSN |
0960-8524 |
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Notes |
PMID:22995170 |
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Call Number |
refbase @ user @ |
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12987 |
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